Polymeric Sensor Fibers Based on a Piezoelectric Polymer and Metal Alloy/Carbon Nanotube/Polymer Composite for Structural Health Monitoring

Abstract

Sensor fibers can be used for structural health monitoring in multiple environmental applications. Possible areas of applications are in geotextiles for monitoring the status of the reinforcement or in wind energy plants to monitor the load on wind blades. In this paper, a new type of sensor fiber based on a piezoelectric polymer (polyvinylidene fluoride) and a composite material made of a thermoplastic polymer, a low melting point metal alloy and carbon nanotubes (CNT) is presented. The piezoelectric polymer generates a signal when a load is applied if it is processed in the right way. Here, the formation of the piezoelectric crystalline structures will be presented. The conductive compound transmits the signal to measurement equipment. While CNT form a conductive network in the polymer, the metal alloy acts as a coating for the nanotubes and increases the electrical conductivity (100 S/m) by two orders of magnitude compared to pure CNT nanocomposites (approx. 1 S/m). The increased conductivity allows the transmission of the signals over larger distances, making the material favourable for large scale applications like wind blades.